• Volume 95, Issue 3

      June 1986,   pages  289-369

    • Production and utilization of frogs: an ecological view

      T J Pandian M Peter Marian

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      The frog producing area in India has been doubled (23–51 million ha) during the last 30 years, while the frog harvest has also been consistently increased by the biology education (3–18 million frogs) and export (17–60 million frogs) sectors. The carrying capacity of the irrigated land is in the range of 28 frogs/ha and a 7% harvest of the population may represent the optimal utilization. Frogs do control agricultural pests but not vectors like mosquitoes. A ban on the frog export from India would mean the loss of not only a revenue of 10 million US dollars/annum but also the jobs for 0–16 million villagers. The need for development of mass culturing techniques of tadpoles, juvenile frogs and ranching of frogs is emphasized.

    • Population dynamics of a tropical lepidopteranCatopsilia crocale (Pieridae)

      M S M Christopher S Mathavan

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      Extensive field observations were undertaken to study the population dynamics of the larvae ofCatopsilia crocale in the Madurai Kamaraj University campus during the years 1980–81 and 1981–82. Though oligophagous,C. crocale adopted ‘monophagic strategy’ for oviposition and larval feeding. Seasonal changes in the nitrogen content of the foodCassia alata leaf influenced the pupal/adult weight and oviposition. Commencement of rain triggered the reproductive activity and continued precipitation facilitated maximum egg deposition. Of total egg production in a year, about 80% was oviposited during northeast monsoon (September–December) and the rest during the south-west monsoon (May–August). Egg, I instar, V instar and pupa suffered more mortality than the other life stages. Of the total number of eggs laid, about 1·01% emerged as adult and 98·99% died during the process of larval and pupal development.

    • Effect of mining activities on the clam fisheries and bottom fauna of Goa estuaries

      A H Parulekar Z A Ansari B S Ingole

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      Comparison of two clam beds and associated benthic fauna, in Mandovi and Cumbarjua canal estuarine system of Goa, severely affected by massive inputs of mining rejects, revealed that, in less than 10 years (1972–73 to 1982–83), high biotic variability induced by increasing environmental stress has caused irreversible ecosystem instability. Reduced dissolved oxygen concentration; high suspended solids and blanketing of bottom deposits by mining rejects, has resulted in more than 70% reduction in clam production; near extinction of resident fauna and the appearance of a low diversity bottom fauna, comprising of tolerant but vagrant species. Ever increasing entry of mining rejects, which has reduced the healthy and highly productive estuarine environment of 1972–73, into an impoverished biotope, in less than 10 years, unless prevented will result in the total extinction of estuarine life in the near future.

    • Biological activity of earthworm casts: An assessment of plant growth promotor levels in the casts

      R V Krishnamoorthy S N Vajranabhaiah

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      Biochemical analyses and auxin and cytokinin bioassays were performed to test the biological activity of wormcasts. Both cellulose paper pulp and soil casts ofLampito mauritii were rich in ammonia, urea, organic carbon content, organic matter, soluble phosphorus and ionic potassium levels. The total nitrogen content of the soil remained unaffected by worm activations. The casts ofLampito mauritii, Pheretima elongata, Pontoscolex corethrurus andOcnerodrilus occidentalis had greater urea levels relative to ammonia levels in contrast to those ofDrawida barwelli, Octochaetoides beatrix andPerionyx excavatus. Worm activations of the leaf compost amended-soils by these species reduced the total phenol levels to varying degree depending on the species examined. Aging and exposures to light reduced the activity levels of these plant growth promotors in the casts ofL. mauritii. A positive correlation between the worm density at the site of soil sampling and the plant growth promotor levels in the samples was obtained. The origin of these promotors from the gut microflora of the worm and their subsequent release into the environment were discussed.

    • The physico-chemical environment and the plankton of managed ponds in Haryana, India

      R N Singhal Swarn Jeet R W Davies

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      An investigation was made of the physical, chemical conditions of the water and substrate of nursery-cum-research-cum-rearing-cum-stocking ponds at Central Inland Fisheries Research Institute, Karnal. Temperature, pH, CO2, dissolved oxygen, chloride, phosphate, alkalinity, nitrates, organic matter, total solids, turbidity, electric conductivity, nitrogen, P2O5, sand, silt, clay, CaCO3, etc. were measured monthly. Statistical analysis of these factors showed some significant correlations. The phyto- and zooplankton were also sampled and the seasonal changes in abundance recorded.

    • Polymorphosis in a brachionid rotifer,Brachionus quadridentatus Hermann from Morar channel, Gwalior (India)

      D N Saksena N Kulkarni

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      Five polymorphic forms, including a new one, of the brachionid rotifer—Brachionus quadridentatus, are described from the Morar channel in Gwalior. These are the nominate formquadridentatus, formcluniorbicularis, formrhenanus, formbrevispina and formmonospina nov. The variation in different morphological forms is due to the emergence, development and elongation of postero-lateral and postero-median spines, and changes in the size of lorica. The present communication forms the first report of polymorphosis inB. quadridentatus from India.


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